Machines for generating curved surfaces



March 13, 1956 E. M. LONG El' AL MACHINES FOR GENERATING CURVED SURFACESFiled Nov. 15, 1954 2 Sheets-Sheet l March 13, 1956 E. M. LONG ETAL2,737,759

MACHINES FOR GENERATING CURVED SURFACES United States Patent o MACHINESnon GENERATING CURVED sUnFAcEs Application November 15, 1954, serial No.468,664

8 Claims. (61.51-96) The present invention relates to machines forgenerating curved surfaces, and more particularly to machines forgenerating torio surfaces on ophthalmic'lenses by grinding.

It has heretofore been diiiicult to devise 'a light and cheaplyconstructed machine for generating toric lenses, particularly where themachine must be easily and quickly adjustable for grinding accuratetoric surfaces over a wide range of curves.V The known machines of thischaracter are heavy and cumbersome and expensive to manufacture due tothe number of slidespivoted parts, heavy bearings, and adjustmentregulating devices required to obtain the proper range of curvesofdiferent radii with the necessary accuracy.

The primary object of the invention is to provide an easily and quicklyadjustable machine for accuratelyf generating curved surfaces over aconsiderable' rangeV of radii, which is also light but strong, andsimple and economical in construction. While the particular embodiments-of the invention hereinafter described andfshown in the drawings aremachines for grinding toric'lenses, it will be apparent that thecombination of-parts` employed may be used in any machine in which thework is to bei swung past a generating tool, or the tooll istobeswungpast the work, in a selected one of a number ofcircular arcs.

Other objects and advantages fof the invention will be apparent from thefollowing description taken in'conneo tion with the accompanyingdrawings,` inwhich:

Figure 1 is a front elevational view of'a machine for grinding concavetoric lenses;

Figure 2 is a fragmentary 'side elevational View thereof;

Figure 3 is a sectional View on the line 3`3 lof-Figure l;

Figure 4 is a plan view of the Vmachine of Figure 1, certain parts beingbroken away;

Figure 5 is an enlarged sectional View on the line 5*S of Figure 3;

Figure 6 is an enlarged sectional view on the line V6 6 of Figure l;

Figure 7 is a rear View of the machine of Figure l;

Figure 8 is a front elevational view of a machine for grinding convextoric lenses;

Figure 9 is a fragmentary" side elevational View thereof;

Figure 1() is a sectional View on the line lll-10 of Figure 8;

Figure l1 is a top plan'view of the 8, certain parts being broken away;

Figure 12 is an enlarged sectional View on the 'line 1li-12 of Figure10;

Figure 13 is a sectional view`on the line 13-13 of Figure 12; and

Figure 14 is a rear view of the machine of Figure 8.

Referring more particularly to Figures 1 to 7 ofthe drawings, themachine illustrated therein is adapted for generating concave `toriclens surfaces byv the known method involving swingingalens blank pastacup-shaped machine of Figure Patented Mar. 13, -1956 grinding wheelrotating about a fixed axis inclined to the axis of swing. In general,the machine 20 comprises a stationary, vertical frame member 21 and aswingable member 22 supported indirectly thereby, one of which memberscarries the generating tool and the other the work holder and work.Since, in the present instance, the tool is substantially heavier thanthe work, it is preferable to mount the grinding wheel 23 on the framemember 21 and the lens holder 24 on the swing membery 22. The weight ofthe swing member 22, lens holder 24 and associated parts is borne by thethin, Aiiexible tension member 25, which may be a steel ribbon or tape,and which is suspended at its upper end from the frame member 21 andV issecured at its lower end to the swing member 22. A rack 26 is verticallyadjustable with respect to the frame 21 by means of a pinion 27rotatable by handwheel 28. The rack 26 carries at its lower end a slideblock 29 adapted to operate in a slideway 3i) on the frame member 21. Asimilar slideway 31 on the swing member 22 is adapted to overlap theslideway 35 and carries a slide block 32 which serves as a bearing for apivot pin 33' threadedly secured to the slide block 29. Hence the pivotpin 33 is slidable with respect to the members 21 and 22 along theslideways 3' and 31 as the rack 26 is adjusted by turning the. handwheel28. In addition to the pivot pin 33, the slide block 29 carries twofulcrum pins 34, and the axes of all three pins are parallel and locatedin the same plane. The two fulcrum pins 34 lie closely adjacent thesteel tape 25 at either side thereof, and are preferably in the form ofrollers which roll along the tape as the rack 26 is adjusted, and haveline contact therewith. The axis of pivot' pin 33 is the axis of swingof the swing member 22 and lies between the lines of contact of thefulcrum rollers 34, which latter define the bending center of the tape25. Hence as the swing memberoscillates about the pivot pin 33, the tape25 acts like a pendulum rod having an axis of osciliation coincidentwith the axis of pin 33.

The machine 12) illustrated in Figures 8 to l-l is adapted for grindingconvex torio lenssurfaces. The machine 129 embodies exactly the sameprinciples as the machine 2i), and the parts of Figures 8 to 14corresponding to those enumerated above for machine 2i) are givencorresponding reference numerals just higher.

Turning again to the concave toric generator' Zi?, the vertical framemember 21 has a horizontal supporting flange'36 adapted to be bolted toaAsuitable table or bench, not shown. A tool supporting plate 3'7 servesto support the' grinding Wheel 23 and associated parts as hereinafterdescribed, and is bolted to the frame member 2l in spaced relationthereto through the medium of legs 38 at either side. The swing member22 is thus enabied to swing freely in the space 39 (Figure 4) betweenthe frame member 21 and plate 37.

The 'front face 41 of framemem'ber 2l and the rear face 42 ofswingmember 22 are both machined iiat, and serve as bearing or guide surfacesduring the oscillations of the swing member. The machined faces 41 'and42 are 'held in abutting, sliding relationship partly by the pivot pin33 and partly by the connector pin e3, which is threaded into the swingmember 22 at 4d (Figure 6). The connector pin 43 extends freely througha slot #i5 in therframe member 21 and serves to connect the swingmember-22 to the lower end of the steel tape 25. For this purpose, ablock 46 is secured to the rear end of pin -43 by a set screw 47, andthe tape 25 is fastened to the block 46 by means of a clamping plate 48and screw 49 (Figures 6, 7).

`The connector pin 43 also serves as a means for connecting anoscillating drive mechanism to the swing member 22. Tor that end,`a"connecting rod Si) is' pivotally mounted on the pin 43 between the framemember 21 and block 46, and is provided with a rack 51 at its outer end(Figures 1, 7). Rack 51 is held in mesh with a pinion 52 by a yoke 53which straddles the pinion and is loosely mounted on the pinion shaft 54(Figure 2). The shaft 54 is journaled in an arm 55 projecting from theplate 37, and may be rotated by either a handwheel 56 or a gear 57secured, respectively, to either end of shaft 54. By turning thehandwheel 56 first in one direction and then the other, the swing member22 may be oscillated about the pivot pin 33. If desired, the swingmember 22 may be oscillated automatically by means not shown, such as anelectric motor controlled by an automatic reversing switch and connectedthrough suitable reduction gearing to the gear S7.

The rear surface of frame member 21 adjacent the slot and the matingsurfaces of connecting rod 59 and block 46 should of course be smoothlyfinished, so that the parts may move freely while serving to hold framemember 21 and swing member 22 together with a sliding fit. is preferablycurved as shown in Figure 5, its lower edge being an arc with radiusslightly greater than the longest radius of swing within the range ofthe machine, and its upper edge being an arc with radius slightly lessthan the shortest radius of swing within that range.

The upper end of steel tape 25 may be secured by means of a clampingplate and screw to a C-shaped support 60 which is suspended from aprojecting portion 61 of the frame member 21, preferably by means of afulcrurn screw 62. By turning the screw 62, the swing member 22 and itsassociated parts may be bodily raised or lowered a small amount, therebypermitting the vertical position of the center of connector pin 43 to beadjusted for a purpose to be later described.

The slideways 39 and 31 may conveniently be in the form of grooves withupper and lower closed ends (Figures 5, 7), and their central portionsmay be cut away to form slots and 66, respectively. These slotsaccommodate the pivot pin 33 and its bearing (formed as part of theslide block 32), and the slot 65 is extended to the upper end of theframe member 21 to permit it to serve as a guideway for thc rack 26. Therack 26 and its pinion 27 are accommodated in a recess at the bottom ofthe above-mentioned frame projection 61 (Figure 6), and the pinion shaft67 is journaled in projection 61 and in a cylindrical boss 68 (Figures1, 3, 7) extending from the side thereof. A thumb screw 69 threaded intoboss 68 (Figures l, 3) permits the shaft 67 and its handwheel 23 to belocked in a desired position of adjustment of the pinion 27 and rack 26.28 of course determines the vertical position of the pvot pin 33 and theassociated fulcrum pins or rollers 34. The rollers 34 are rotatablymounted on studs 7 t) screwed into the slide block 29 and maintained incorrect alignment by the spacer plate 71.

A bar 73 screwed to the front of fratrie member 21 (Figures l, 5)assists in retaining the rack 26 in slot 65, and also carries an indexmark 74 cooperating with a scale 75 on the rack. The scale 75 ispreferably graduated in diopters and measures the distance between thecenters of pivot pin 33 and connector pin 43. The index 74 and scale 75may be properly correlated or zeroed in by adjusting screw 62 to varythe position of connector pin 43 as above described.

A trough 78 is fixed to the lower end of swing member 22 andaccommodates the work holder 24 which is adjustable longitudinally ofthe trough and swing member by means of a screw St? and handwheel 81.The trough 78 may be provided with the usual means (not shown) forcirculating liquid coolant or the like. The holder 24 is adapted to holda conventional lens block 82 to which a lens blank 83 may be adhesivelysecured in customary manner. Adjustment of the handwheel 81 moves thelens blank 83 toward or away from the grinding wheel 23 and permitsregulation of the thickness of the finished Slot 45 The adjustment ofhandwheel lens as later described. The axis of screw is parallel tomachined face 42 of swing member 22. As is customary, the lens blank 83should be so mounted on the lens block 82, and the latter should be soheld in the holder 24, that the axes of the lens and of the grindingwheel 23 lie in a common plane perpendicular to the axis of swing (theaxis of pivot pin 33), and hence parallel to face 42.

We may now turn to the means for supporting and adjusting the grindingwheel 23. The front face of tool supporting plate 37 has a verticallyextending dovetail groove 85 (Figure 4) in which is slidably mounted atongue on the back of a vertical slide 86. The front of slide 86 isformed with a raised quadrant 37 having an arcuate groove 88, which isT-shaped in cross-section. A tool base 89 is pivoted to the quadrant 87at 90 (Figure 6), and is provided with a locking lug 91 adapted to slidein the groove 88 and to be locked therein at a desired position ofadjustment by a handle 92, in well-known manner.

The tool base 89 has a dovetail groove 93 in which is slidably mounted atool post 94, which may be locked in the desired position inconventional manner. A tool shaft is journaled in the tool post 94parallel to the flat bearing surfaces 41 and 42. The shaft 95 carries atone end the cup-shaped grinding wheel 23, and is driven by a motor 96bolted to the other end of the tool post 94 and connected to an electricpower source by a flexible cable 97. A suitable scale, not shown, may beplaced near the curved edge of quadrant 87, so that the angular settingof tool shaft 95 may be read off the scale.

The vertical slide 86 may be bodily raised or lowered, carrying with itthe quadrant 87 and grinding wheel 23, by turning a handwheel 98 in theappropriate direction. The handwheel 98 has a shaft 99 journaled inbosses 1GO formed on arm 55 of plate 37, which shaft carries a spiralgear 101 meshing with a spiral gear 102 (Figures l, 2). A spool 103 issecured to the spiral gear 102 to rotate therewith, and both are mountedon a vertical shaft 104 fastened to the arm 55. The upper end of shaft134 is threaded and cooperates with threads in spool 1173, so that spool103 and gear 102 rise or fall as they turn about shaft 104 in onedirection or the other. A lever 105 is pivoted at its center to theplate 37 (Figure 1), and has a block 106 pivoted to each of its ends.Looking toward the front of the machine (Figure l), the right hand block106 is retained within the rims of spool 193 (Figure 2), and hence theleft hand end of lever is lowered as spool 103 is raised, and viceversa. The left hand block 106 is retained within a recess at the backof an extension 107 at the upper end of slide 86, and hence serves toraise or lower the slide as it goes up or down.

Scale 11i) and pointer 111 are provided for indicating thc extent ofvertical movement of slide 86 and grinding wheel 23. The scale 110 isfixed to plate 37 and pointer 111 is pivotally secured thereto (Figurel). An arm 112 fastened to the top of vertical slide 86 and projectingsidewise therefrom carries a regulating screw 113 which bears on thelower end of pointer 111, in such manner that the pointer is moved tothe right across scale 116 as the slide 86 is lowered. A biasing spring(not shown) urges pointer 111 toward its left hand extreme position andreturns it in that direction as vertical slide 86 is raised. Theregulating screw 113 should be adjusted so that the pointer 111 readszero at the right end of scale 119 when the vertical slide 36 is loweredto such position that the axis of tool base pivot 90 is aligned with thecenter of connector pin 43 when the swing member 22 is vertical. InFigure l, the pointer 111 is shown in the above described zero position,and the corresponding aligned positions of pivot 90 and pin 43 may beseen in Figure 6. The center of connector pin 43 thus affords a commonstarting point for the measurements made with both scales 75 and 110, ashereinafter described.

While the scale 110 is thus properly zeroed, the grinding wheel 23, toolshaft 95and toolpost 94 should be adjusted relative to each other and tothev tool base 89, so that the arcuate working edge of thev grindingwheel is4 properly aligned with respect to the' axis ofrtool base pivot9i), and the grinding wheelaxis lies in a yplane perpendicular to theaxis of the pivot pin 33-n about which the swing member 22 oscillates.The scale 110 then measures any vertical displacement of grinding wheel23 from the above-described aligned or reference position. Before themachine is placed in operation, the scales 75 and 11G should be zeroedand the foregoing adjustments made. Thereafter', periodical checksshould of course be made to detect and correct for wear or other factorsthat may have caused mal-adjustment.

The operation of the machine is extremely simple and follows a patternwell-known to those skilled in the art of generating toric lenses. Theoperator is` usually provided with a lens blank properly aixed `to alens block andwith instructions regarding the `finishing of the lens andthe necessary machine' settings referred to below.

By releasing the handle 92, the tool base 89 maybe swung about its pivot90 until the grinding wheel-axis has the prescribed angularity tothevertical, and the handle 92 is then moved to lockedl position. Thisangular adjustment will not disturb the adjustments-described above ashaving been made before operation commences, and, together with thewheel size, xes the' cross curve of the toric surface to be generated inknown manner. Handwheel 23 may now be turned until scale'75 on rack 26reads the specified base curve radius.

The operator now raises the ,grinding wheel 23 by turning handwheel 98until pointer 111 Vswings to a point which indicates on scale 110 thethicknessof glass that it has been determined in the usual manner shallbe removed from the lens blank. Having fastened the lens block 82 in'the holder 24, the operator turns the handwheel 81, with the swingmember 22 in vertical position, until the lens blank just contactsv thegrinding wheel.

The swing member 22 isthen'swung to one side by turning handwheel 56,and the motor 96 turned on. The grinding wheel 23 is now lowered, bymeans of handwheel 98, a distance equal to the desiredrdepth of firstcut, as indicated by the movement of pointer 111 over scale 110. Theswing member 22 is now swung tofthe other side and preferably back againto the side from whichl it started, so that the lens blank passes therotating grinding wheel in both directions. The grinding wheel 23 isthen lowered the desiredv amount for the second cut,` and the grindingpasses repeated. Successive cuts'are -made in this manner until pointer111 reaches'its zero mark, when the final passes are made.

At the conclusion of the foregoing operation, `when the swing member 22is vertical, thel grindingfwheel will just contact the lens blank whilepointer 111 will indicate zero on scale 110. 1n this condition, bothvthe axis of tool base pivot 90 and the working edge of grinding wheel 23are aligned with the center of connector pin 43. Moreover, the distancebetween the center of connector pin 43 and the axis of pivot pin 33(which is the same as the distance in diopters shownon scale 75) is thebase curve radius, that is to say, the radius of curvature of the uppersurface of the lens blank in the direction of swing of the swing member22. Assuming the tool base 89 was set at the correct angle on thequadrant 87, vthe desired cross curve will have been ground on the lenssurface at the same time as the base curve.

Referring now to Figures 8 to 14, the machine 120 there shown is, asalready stated, the counterpart of machine with such modifications asare desirableV to adapt machine 120 to grind convex toric lens surfaces.The principal changes are due to the fact that in machine 1211 the lensblank must be located above the axis of swing of the swingrrmemberrather vthan below it as in machine 20. The parts numbered from 121 to134 are 6 identical in general purpose and effect tothe correspondinglynumbered parts 21 to 34-of machine-20,' but this direct correspondenceydoes not always exist for higher reference numbers. However, so far'aspossible, corresponding reference numerals differing by 160 are usedthroughout for the two machines.

The vertical'frame member 121 may be bolted to a suitable table orbench, not shown, through the two horizontal supporting flanges 136 ateither side of the machine (Figures l0, 14). A substantially rectangularboss 137, integral with frame member 121 at its upper left corner(Figure l2) and located above 'the swing member 122, serves to supportthe grindingrwheel 123 and associated parts as hereinafter described.

TheV flat, machined faces 141 of frame member 121 and 142 of swingmember 122 are held inabutting, sliding relationship not only by thepivot pin 133 -and the connector pin 143, but also bythe drivepin 144.The functions of the connector pin 43 of machine 20am, in effect,divided between the connector pin 143 andidrive pin 144 of machine 120.`The connector pin 143 serves to connect the lower end of swing member122 to the lowerend of the steel tape below the frame member 121, whilethe drive pin 144 extends through slot 145 in the frame member andcarries, pivotally mounted thereon, the connecting rod having a rack 151for oscillating the swing member 122 about thepivot pin 133 (Figures 13,14). Rack 151 is held in mesh with pinion 152 -by a roller 153 mountedonjarm 155 projecting from frame member 121, in which arm pinion shaft154 is joiurnaled (Figures 8, 9). Pinion shaft 154 may be rotated by ahandwheel 156 for oscillating the swing member 122. As before, a gear157 is provided on the pinion shaft 154 for oscillating the swingmember122 automatically if desired.

The upper end of steel tape 125 is secured to one end ofa lever 158(Figure 14) pivotally mounted on a stud 159 fastened to the back offrame member 121. A regulating screw 162 bearsron the other end of lever15S, and permits the center of connector pin 143 to be adjustedvertically by a'small amount.

As before, the`slots 165 and 166 (Figures l2, 13)v at the centers of theslideways 130 and 131, respectively, accommodate the pivot pin 133-anditsl bearing (formed aspart of the slide block 132). The rack 126,lpinion 127 andlpinion shaftf167, however, are accommodated inanrextension armj168 bolted tothe rear of frame member 121 at its upperend. (Figures 10,- 13) and provided with a cylindrical boss 168extending to the left of the machine as viewed from the front (Figuresl, 12). HandwheellZS is secured to, pinion shaft-167- at the outer endof boss 168. vA thumb screw- 169 threaded into arm 168 (Figures 10,12)"permits the rack 126 to be locked in a desired position `of verticaladjustment. The fulcrum lpins or rollers 134 are rotatably mounted onstuds 170 screwed into the slide block129 and carried by the anglebracket 172 which is fastened to the bottom of rack-126 (Figures l0,13). The studs 170 thus serve to connect rack 126 to slide block 129 aswell as to rotatably support the rollers 134, whereas the correspondingstuds 70 of machine 20 perform only the latter function. The adjustmentof handwheel 128 and raek`126 of course determines the verticalpositionof pivot pin 133 and the associated rollers 134.

Bar 173, index mark 174 and scale 175 (Figures 8, l2) correspondfunctionally to. parts 73, 74 and 75 of machine 20, except that scale175 Vmeasures the distance in diopters between the centers of pivotl pin133 and drivepin 144. As before, scale 17S may be properly zeroed byadjusting screw 162, since drive pin 144 4is carried by swing member 122and hence moves with connectorv pin 143 as it is raised or lowered byscrew 162 as above described. Also thetrough Y178, work holder 124- andthe -associated parts -183 correspondr to the similarly numbered partsof machine 20, but, asV indicated above,

trough 178 is bolted to swing member 122 adjacent its upper end.

A dovetailgroove 185 in boss 137 (Figure 12) accommodates a tongue 186on the back of quadrant 187 (Figure 1l). From there on, the means forsupporting and driving the grinding wheel 123 are practically identicalto the corresponding parts of machine 20, and hence detailed descriptionthereof is unnecessary for machine 120. The corresponding parts arenumbered according to the scheme previously employed, ending with motor196.

As before, handwheel 198 operates the means for raising or lowering thequadrant 187 and with it the grinding wheel 123, and this means includesspool 203 threaded on vertical shaft 204 and lever 205. But spool 203 isdirectly secured to handwheel 198 so that the two rise or fall togetheras they turn about shaft 204. Shaft 204 is fastened to an arm 200extending sidewise from the top of frame member 121, and lever 205 ispivoted to an ear 201 projecting upward from the top of frame member121. The two arms of lever 205 are offset, and the left hand end oflever 205 is pivotally connected by a link 206 to the upper portion ofquadrant 187 (Figures 10, ll). The right hand end of lever 205 carries aroller 208 which cooperates with the rims of spool 203 (Figures 8, 9).

The arm 200 also carries a scale 210 which is the same functionally asscale 110 of machine 20. Pointer 211 is pivoted to frame member 121 sothat its outer end traverses scale 210 and its inner end engages aprojecting portion of quadrant 187 to be raised or lowered thereby, InFigure 8, the pointer 211 is shown in the zero position that it occupieswhen the axis of tool base pivot 190 is aligned with the center of drivepin 144 (see Figure 10). The center of drive pin 144 thus affords acommon starting point for the measurements made with both scales 175 and210.

The operation of machine 120 is on all fours with that of machine 20.Indeed, by raising the reference numerals by 100, the description of theoperation of machine will fit machine 120 exactly.

It has been determined experimentally that machines built in accordancewith the herein disclosed machines 20 and 120 can be adjusted to operatewith great accuracy and will generate commercially satisfactory concaveand convex toric surfaces on ophthalmic lenses over the ranges of baseand cross curves usually required. Of course, it will be understood thatthe generated lens surfaces must be subjected to subsequent finishingoperations.

lt will be apparent that a different arrangement of parts would enablethe tool to be swung past the work instead of vice versa as in machines20 and 120. Also, by a considerable redesign, but without departing fromthe essentials of the herein disclosed machines, it would be possible tocombine the functions of generating concave and convex toric surfaces ina single machine.

While there are herein described, and in the drawings shown,illustrative embodiments of the invention, it is to be understood thatthe invention is not limited thereto, but may comprehend otherconstructions, arrangements of parts, details and features withoutdeparting from the spirit of the invention. We desire to be limited,therefore, only by the scope of the appended claims.

We claim:

1. A machine for generating curved surfaces comprising a frame member, aswing member adapted for oscillation about a predetermined axis withrespect to said frame member, a generating tool carried by one saidmember and a work holder carried by the other said member, slidewayslongitudinally disposed on said members, pivotally connected slideblocks slidably mounted in said slideways and adjustable therealong, athin exible tension member for supporting said swing member, saidtension member being suspended at its upper end from said frame memberand having its lower end secured to said swing member, and fulcrum meansfor said tension member carried by said slide blocks and havingsubstantially line contact with said tension member at either sidethereof in substantially the same plane as the axis of said pivotalconnection between the slide blocks, whereby the latter axis coincideswith the axis of oscillation of said tension member and defines saidpredetermined axis.

2. The combination as claimed in claim l in which said fulcrum meanscomprises two rollers rotatably mounted on the block that slides in theframe member slideway.

3. The combination as claimed in claim l in which said tension member issuspended from said frame member at a point lying above and centrally ofthe frame member slideway and said tension member is secured to saidswing member at a point lying below and centrally of the swing memberslideway.

4. The combination as claimed in claim l in which a rack and pinionmechanism is used for slidably adjusting said slide blocks along saidslideways.

5. A machine for generating toric surfaces on lenses comprising a framemember, a swing member adapted for oscillation about a predeterminedaxis with respect to said frame member, a grinding wheel adjustablymounted on one said member and a lens holder adjustably mounted on theother said member, slideways longitudinally disposed on said members,pivotally connected slide blocks slidably mounted in said slideways andadjustable therealong, a thin flexible tension member for supportingsaid swing member, said tension member being suspended at its upper endfrom said frame member and having its lower end secured to said swingmember, and fulcrum means for said tension member mounted on the blockthat slides in the frame member slideway, said fulcrum means havingsubstantially line contact with said tension member at either sidethereof in substantially the same plane as the axis of said pivotalconnection between the slide blocks, whereby the latter axis coincideswith the axis of oscillation of the tension member and defines saidpredetermined axis.

6. A machine for generating toric surfaces on lenses comprising a framemember, a swing member adapted for oscillation about a predeterminedaxis with respect to said frame member, a grinding wheel mounted on saidframe member for adjustment of the Wheel axis angularly with respect tothe vertical axis of the frame member, a lens holder mounted on saidswing member for adjustment longitudinally thereof, slidewayslongitudinally disposed on said members, pivotally connected slideblocks slidably mounted in said slideways and adjustable therealong, athin flexible tension member for supporting said swing member, saidtension member being suspended at its upper end from said frame memberand having its lower end secured to said swing member, and fulcrum meansfor said tension member mounted on the block that slides in the framemember slideway, said fulcrum means having substantially line Contactwith said tension member at either side thereof in substantially thesame plane as the axis of said pivotal connection between thc slideblocks, whereby the latter axis coincides with the axis of oscillationof the tension member and defines said predetermined axis.

7. A machine for generating toric surfaces on lenses comprising a framemember, a swing member adapted for oscillation about a predeterminedaxis with respect to said frame member, a grinding wheel mounted on saidframe member for adjustment of the wheel axis angularly with respect tothe vertical axis of the frame member, a lens holder mounted on saidswing member for adjustment longitudinally thereof, slidewayslongitudinally disposed on said members, pivotally connected slideblocks slidably mounted in said slideways and adjustable therealong, athin flexible tension member for supporting said swing member, saidtension member being suspended at its upper end from said frame memberabove and centrally of its slideway and having its lower end secured tosaid swing member below and centrally of its slideway, and fulcrumrollers for said tension member rotatably mounted on the block thatslides in the frame member slideway, said fulcrum rollers havingsubstantially line contact with said tension member at either sidethereof in substantially the same plane as the axis of said pivotalconnection between the slide blocks, whereby the latter axis coincideswith the axis of oscillation of the tension member and defines saidpredetermined axis.

8. A machine for generating toric surfaces on lenses comprising a framemember, a swing member oscillatable with respect to said frame member, athin flexible tension member for supporting said swing member l5 fromsaid frame member, means for adjusting the position of the axis of saidswing member rectilinearly, a slide adjustable rectilinearly on saidframe member, a tool base pivoted on said slide for angular adjustmentthereon about an axis parallel to the axis of oscillation of said swingmember, a lens holder mounted on said swing member, a grinding wheelrotatably mounted on said tool base, and means including a connectingrod that is pivotally connected to said swing member for oscillatingsaid swing member, the pivot of said connecting rod and the axis aboutwhich said tool base is angularly adjustable coinciding in the zeroposition of the rectilinear adjustments of said swing member and of said10 slide.

References Cited in the file of this patent UNITED STATES PATENTS1,984,074 McCabe Dec. 1l, 1934 2,556,604 Suddarth June 12, 19512,620,600 Janatka Dec. 9, 1952 2,633,675 Ellis Apr. 7, 1953 2,649,667Cooke Aug. 25, 1953

